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iMac Intel 27" EMC 2309 (Late 2009, Core 2 Duo 3.06 or 3.33 GHz) ID iMac10,1, EMC 2374 (Late 2009, Core i5 2.66 GHz or Core i7 2.8 GHz) ID iMac11,1

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Hello guys!

I have an iMac A1312 27"

It was working properly but NOW it turns on make the Apple CHIME. but SCREEN is totally DEAD (NO VIDEO).

At first I tought it was the POWER SUPPLY for the LCD. I changed it with a brand new ONE. NOTHING HAPPENED.

Then I started to think that it is related to the connector on the logic board and I am thinking right now to REFLOW it. What do you guys thinks?

I heard that it may be the GRAPHIC card. BUT when I use the THUNDERBOLT to an external display it works fine.

The computers works 100% fine but dont GIVE image to its own LCD.

Sometimes I think there is no energy going through the LCD cause if the CONNECTION from the LCD to the logic board is not good it stills could produce some energy like a MONITOR without anything plugged at it. DOESNT it?


Отвечено! Посмотреть ответ У меня та же проблема

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Do you have a spare working screen around to test? Usually is the screen on this model.


@angelorecaman You appear to be repairing Apple products professionally. Would you mind expanding your profile so we can get to know you better?



What kind of info do you need? On the menu MY PROFILE nothing that I need to update!


You are correct Angelo, after looking over your questions I know all I want about you. @oldturkey03 may be more able to help you than I. Mike what do think of our Sanguisugæ OP?



did you get solution or not yet,I have Exactly the same issue imac 27" 2011


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Выбранное решение

I'd start by following Deep dive suggestions from Apple but would stop at #7

Deep Dive

1. Verify boot chime present and fans running when computer powered ON. (Reset SMC and clear PRAM if necessary for proper boot up.)

Yes Power on self test OK.

Go to step 2.

No Go to Won’t Start Up symptom flow.

2. Verify if image is visible on built-in LCD panel, with adjustable backlight level.

Yes Video present. Verify system functionality and return to user or go to appropriate troubleshooting flow.

No Go to step 3.

3. Connect supported external display. Verify if image appears on external display when system is booted.

Yes External display detected by system. Video circuitry on logic board functional.

Go to step 4.

No Go to No Video symptom flow.

4. Verify if LCD backlight is ON by looking for faint glow from display when viewed in darkened room with brightness set at maximum.

Yes LED backlight is functioning.

Go to step 7.

No Go to step 5.

5. Shine bright (low heat) flashlight onto front of LCD. With computer powered ON verify if a faint image is visible.

Yes LCD panel functional but backlight is missing or dim. Remove LCD panel and inspect and reseat the

following cable connections:

-Backlight power cable

between backlight board and LCD panel.

-Vertical sync cable between backlight board and LCD panel.

-DC power cable to backlight board and power supply.

Replace any damaged cable.

Reinstall LCD panel and go to step 6.

No No image or backlight.

Go to step 7.

6. Power ON system. Verify if image is now visible on LCD panel with correct backlight level.

Yes Issue resolved.

No Replace LED backlight board.

Retest. If issue persists, go to step 7.

7. Inspect and reseat internal DisplayPort cable (between logic board and LCD panel).

Power ON system. Verify if image is visible on built-in LCD display.

Yes Issue resolved.

No Replace internal DisplayPort cable.

If issue persists, replace LCD panel. Run Apple Service Display Utility to verify the resolution of intermittent display flickering symptoms. If the Apple Service Display Utility fails, contact Technical Service Provider Support

Anything after that, you'd have to measure some voltages on your logicboard.

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I already tested everything and IT IS the display connector on the logic board. Do you have a video/tutorial that shows how to REPLACE it?



@angelorecaman you did not say that you had already checked that. Anyhow this video shows how to replace the connector https://www.youtube.com/watch?v=M4POV5jn...


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Этот ответ изначально был на другой вопрос.

Try it with an external monitor. This model has issues with the GPU solder. Let us know your results.

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I already tried with an external monitor and it works 100%, so I guess it is some issue related to the LCD.


-Tested with a NEW LCD,

-Tested with a NEW INVERTER



What I am assuming is that something RELATED to the inverter is not working. Cause if was the LOGIC BOARD CONNECTOR the LCD should turn on and bright even in a glowing dark image. but it seems to be DEAD no energy at all.

Since I already tried a new INVERTER I am starting to think it is something related to the CABLES that bring energy to the INVERTER.

What do you think?



What do you think?

Actually I already TRIED new cables. Shouldn´t the LCD glow if the inverter is ok but the LOGIC BOARD connector is not?


Not if you have issues with your Panel power control circuitry.....


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I have the same 27 inch iMac 2009 model. I get a clean start up with chime and fans running but can not get a video image. not even with an external monitor. I know the power supply is good, the backlight board is good and the video card is good as well. Any ideas anyone?

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was this resolved? I have same machine and same symptoms with new HD. I am going to replace the Vsync ribbon, but would like to verify if the video card is loose. Do you know where it is?


on a 27 inch iMac 2009 i7 I had the same problem, it was due to the temperature sensor of the LCD panel. Apple uses a 2N3904 transistor as a standard component which is easy to get in electronics stores for 1-2 €. Pay attention to how it is soldered.

I came to this through the tool HWSensors, which displays the measured values of all (?) Temperature sensors, for the LCD sensor it showed over 130 ° C, which could not be correct.


Interesting, im going to have to try this on my 2011


I have exactly the same problem.

My iMac is an A2115 3.6GHz.

It works OK with an external monitor, but the iMac fan goes at full blast.

When started the main LCD is black. On the external monitor if I go into settings/Displays only the external monior shows up.

What I have replaced/tried.

I have tried all the usual software fixes, but since the iMac works with the external monitor I figure the mainboard and software is fine.

I replaced the LCDTemperature sensor.


I purchased a new LCD and replaced the sensor and LVDS cables to it and installed it in the iMac.

After all this it still goes to a black screen with the fans going full bore.

Booting into Recovery makes no difference.

Any other ideas anyone??


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I am using 2012 and 2013 27 inches. Both have the same symptoms. It works well when connected to an external monitor. However, only a black screen appears on the internal display. When you shine a light on it, the screen appears very dark.

I thought this was a screen issue. However, it is assumed that the problem is not with the liquid crystal display, but with the chip responsible for the backlight on the logic board. What do you think? I found this symptom on my MacBook Pro. Data on iMac is difficult to find.

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@paparapha yes that sounds like a backlight issue. Could be anything from the WLED driver, backlight fuse to the backlight itself. You need at least a multimeter to start troubleshooting.


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Angelo Recaman будет вечно благодарен.
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